title: Pharmacological characterization of alpha-adrenoceptors in the bovine median caudal artery.
abstract: This study was initiated to characterize alpha-adrenoceptors in the isolated bovine median caudal (tail) artery preparation for use as a model of blood vessels in the extremities of cattle. Prazosin shifted the concentration-response relationship for noradrenaline and phenylephrine to the right with pA2 values of 8.74 and 9.04, respectively. Against noradrenaline, phentolamine yielded a pA2 of 7.36. The concentration-response relationship for medetomidine was not inhibited by rauwolscine or idazoxan. The noradrenaline KA was 3.11 microM. These results suggest that catecholamines elicit alpha-adrenoceptor-mediated contractions primarily through alpha1-adrenoceptors and not alpha2-adrenoceptors.
authors.affiliation: Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames 50011-1250, USA.
authors.forename: B J
authors.initials: BJ
authors.lastname: Hill
authors.forename: D C
authors.initials: DC
authors.lastname: Dyer
mesh_terms: D000316:Adrenergic alpha-Agonists / Q000378:metabolism*; D000317:Adrenergic alpha-Antagonists / Q000737:chemistry / Q000494:pharmacology*; D000818:Animals; D001158:Arteries / Q000737:chemistry; D001667:Binding, Competitive; D002417:Cattle; D004305:Dose-Response Relationship, Drug; D005260:Female; D008297:Male; D009638:Norepinephrine / Q000378:metabolism*; D010646:Phentolamine / Q000737:chemistry / Q000494:pharmacology; D010656:Phenylephrine / Q000737:chemistry / Q000494:pharmacology; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects* / Q000378:metabolism; D013623:Tail / Q000098:blood supply*
chemical_list: D000316:Adrenergic alpha-Agonists; D000317:Adrenergic alpha-Antagonists; D011942:Receptors, Adrenergic, alpha; D010656:Phenylephrine; D009638:Norepinephrine; D010646:Phentolamine